Method for extending ranging region in an ofdma system

Abstract

A method for uplink synchronization, in a wireless communication device, with a base station in a wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA) is disclosed. The method comprises selecting ( 440 ), by the wireless communication device, at least one ranging slot randomly from ranging slots in at least a transition gap. The wireless communication device further transmits ( 445 ) at least one ranging code in the selected at least one ranging slot.

1 . A method for uplink synchronization, in a wireless communication device, with a base station in a wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA), comprising:
 selecting, by the wireless communication device, at least one ranging slot randomly from ranging slots in at least a transition gap; and   transmitting, by the wireless communication device, at least one ranging code in the selected at least one ranging slot.   
   
   
       2 . The method of  claim 1 , wherein the at least one ranging slot is at least one symbol time long. 
   
   
       3 . The method of  claim 2 , wherein the at least one ranging slot is an initial ranging slot. 
   
   
       4 . The method of  claim 2 , wherein the at least one ranging slot is a handoff request ranging slot. 
   
   
       5 . The method of  claim 2 , wherein the at least one ranging slot is a periodic ranging slot. 
   
   
       6 . The method of  claim 2 , wherein the at least one ranging slot is a bandwidth request ranging slot. 
   
   
       7 . The method of  claim 1 , wherein the selected at least one ranging slot is entirely in the transition gap. 
   
   
       8 . The method of  claim 1 , further comprising:
 monitoring, by the wireless communication device, multiple pilot channel signals of multiple frequency bands;   detecting, by the wireless communication device, a pilot channel signal, from the multiple pilot channel signals, having a highest power;   tuning, by the wireless communication device, to a frequency band, from the multiple frequency bands, corresponding to the pilot channel signal; and   synchronizing, by the wireless communication device, with a downlink sub-frame received in the frequency band, before the selecting.   
   
   
       9 . The method of  claim 8  further comprising:
 receiving, by the wireless communication device, parameters that inform the wireless communication device that ranging slots are in at least the transition gap.   
   
   
       10 . The method of  claim 9  further comprising:
 receiving, by the wireless communication device, in a downlink sub-frame, parameters that inform the wireless communication device that the wireless communication device is permitted to use the ranging slots in the transition gap.   
   
   
       11 . The method of  claim 1 , wherein the wireless communication device is pre-programmed to use ranging slots in the transition gap. 
   
   
       12 . The method of  claim 1 , wherein the ranging slots are also in an uplink sub-frame. 
   
   
       13 . The method of  claim 12 , wherein the ranging slots in the uplink sub-frame are at a beginning of the uplink sub-frame. 
   
   
       14 . The method of  claim 13 , wherein the transition gap is a transmit/receive transition gap. 
   
   
       15 . The method of  claim 12 , wherein the ranging slots in the uplink sub-frame are at tail end of the uplink sub-frame. 
   
   
       16 . The method of  claim 15 , wherein the transition gap is a receive/transmit transition gap. 
   
   
       17 . The method of  claim 1 , wherein the at least one ranging code is an initial ranging code, randomly chosen from a plurality of codes used for initial ranging. 
   
   
       18 . The method of  claim 1 , wherein the transition gap is at least one symbol time long. 
   
   
       19 . The method of  claim 1 , further comprising:
 receiving, by the wireless communication device, a ranging response message from the base station, after transmitting.   
   
   
       20 . The method of  claim 19 , wherein the ranging response message is an initial ranging response message. 
   
   
       21 . A method for uplink synchronization between a base station and a wireless communication device in a wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA), comprising:
 receiving, by the base station, at least one ranging code in a ranging slot, wherein the ranging slot is at least partially located in a transition gap.   
   
   
       22 . The method of  claim 21  further comprising:
 broadcasting, by the base station, parameters to inform the wireless communication device that the wireless communication device is permitted to use the ranging slot in the transition gap, before the receiving.   
   
   
       23 . The method of  claim 21  further comprising:
 broadcasting, by the base station, in a downlink sub-frame, parameters to inform the wireless communication device that the wireless communication device is permitted to use the ranging slot in the transition gap, before the receiving.   
   
   
       24 . The method of  claim 21 , wherein the ranging slot is an initial ranging slot and the at least one ranging code is an initial ranging code. 
   
   
       25 . The method of  claim 21 , further comprising, after the receiving:
 calculating, by the base station, adjustment information, wherein the adjustment information includes at least a frequency adjustment, a timing adjustment, or a power adjustment; and   broadcasting, by the base station, an initial ranging response, wherein the initial ranging response contains the adjustment information.